JP2000291536A - Fluid force-feeding pump and hydraulic cylinder thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve working efficiency in a fluid force-feeding pump and a hydraulic cylinder therefor by setting a stroke length of a piston according to properties of a fluid like a slurry fluid, such as ready mixed concrete, earth and sand, soft soil,.or the like, at the time of forcibly feeding the fluid with the piston. SOLUTION: In this pump, plural bypass ports P1-P3 are provided along hydraulic cylinders 3a, 3b to form bypass circuits BP1-BP3, while the bypass circuits BP1-BP3 are provided with gate valves V3, V4, which are capable of opening and closing to select the bypass circuit BP1-BP3. Pistons 4a, 4b are disposed in the hydraulic cylinders 3a, 3b, such that hydraulic oil in one of the hydraulic cylinders 3a, 3b flows into the other of the hydraulic cylinders 3a, 3b through one of the bypass circuits BP1-BP3 and stops at that position, when the piston 4a, 4b passes the port position where one of the gate valves V3, V4 opens. Thereby, stroke lengths of the pistons 4a, 4b can be selected according to set positions set on the basis of design specifications of the bypass ports Pi-P3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a ready-mixed concrete,
The present invention relates to an improvement of a fluid pump for pumping a fluid such as a slurry fluid such as soil and soft soil by a piston.

[0002]

2. Description of the Related Art Conventional fluid pumps, for example, piston-type concrete pumps are known from tunnels, caisson,
It is used to pump concrete in narrow places such as bridges and buildings, and to pump concrete through iron pipes by reciprocating a plunger by mechanical force or hydraulic pressure. Has become.

[0003] Two types of hydraulic cylinders of the piston type concrete pump, a variable type in which the piston stroke length is variable and a fixed type, are conventionally used. The variable type is capable of adjusting the stroke length by increasing or decreasing the amount of hydraulic oil in a closed circuit formed by connecting the head side or the rod side of two cylinders,
In addition, the above-mentioned fixed type is configured to forcibly adjust the amount of hydraulic oil in a closed circuit formed by connecting one side of two cylinders like the variable type, and to always operate with a constant stroke length. ing.

[0004] A conventional example of a hydraulic concrete pump having, for example, a pair of hydraulic cylinders as shown in FIGS. 8A, 8B and 10 will be described.
The high-pressure hydraulic oil obtained by the above enters the hydraulic switching valve block 2 and a pair of first and second hydraulic cylinders 3a, 3 of a hydraulic concrete pump for pumping concrete.
and the swing switching hydraulic cylinder SC for switching the swing valve 31.

The hydraulic switching valve block 2 includes a main relief valve 5, a switching valve 6 of a pair of hydraulic cylinders 3 of a hydraulic concrete pump, and a swing switching hydraulic cylinder S.
And a switching valve 6 for controlling the flow of hydraulic oil in one of the first hydraulic cylinder 3a and the other hydraulic cylinder 3b of the pair of hydraulic cylinders of the hydraulic concrete pump. The switching pilot pressure of the switching valve 6 is controlled by the pilot pressure switching valve 8 based on electric signals from the position detection switches 11a and 11b of the piston PS of the swing switching hydraulic cylinder SC.
The other switching valve 7 controls the flow of hydraulic oil of the swing switching hydraulic cylinder SC, and the switching pilot pressure of the switching valve 7 is applied to one end and the other end of the first hydraulic cylinder 3a of the hydraulic concrete pump. An electric signal from the first and second position detection switches S1 and S2 of the installed first piston 4a is controlled by a pilot pressure switching valve 9.

That is, the first and second hydraulic cylinders 3a and 3b are driven by the switching valve 6, and the first and second hydraulic cylinders 3a and 3b are driven.
The switching valve 7 is controlled by switching between a and 3b, the swing switching hydraulic cylinder SC is driven by switching of the switching valve 7, and the switching valve 6 is controlled by switching the swing switching hydraulic cylinder SC. is there.
Also, the first piston 4a of the first hydraulic cylinder 3a
Is operating in the direction of the arrow shown in FIG. 8, the solenoid valve 12 of the pilot pressure switching valve 9 is closed and the solenoid valve 1 of the other pilot pressure switching valve 9 is closed.
5 is closed, and when the first piston 4a of the first hydraulic cylinder 3a reaches the stroke end on the other end side, an electric signal detected by the position detection switch S2 energizes the solenoid valve 14 of the pilot pressure switching valve 9. And the switching valve 7
Hydraulic fluid flows through the hydraulic cylinder S for swing switching.
The piston PS of C operates upward from below in the direction of the arrow shown in FIG. 8A, and switches the swing pipe 31 to the left position 31L as shown by the two-dot chain line in FIG.

When the piston PS of the swing switching hydraulic cylinder SC moves to the stroke end, an electric signal is output from the position detection switch 11b and the pilot pressure switching valve 8
8A is energized to the other solenoid valve 13 of FIG.
The switching valve 6 is switched in the opposite direction from below to above, and the first and second pistons 4a and 4b of the first and second hydraulic cylinders 3a and 3b are moved in the direction opposite to the arrow shown in FIG. Operate.

Then, from the state shown in FIG. 8A, the second piston 4b of the second hydraulic cylinder 3b reaches the stroke end on the other end side of the second hydraulic cylinder 4b as shown in FIG. When the one piston 4a does not reach the position detection switch S1 provided at one end of the first hydraulic cylinder 3a, the operation of the closed circuit M configured by connecting the head sides of the first and second hydraulic cylinders 3a and 3b to each other. This is because there is too much oil, and an excess amount of hydraulic oil in the closed circuit M is supplied to the reservoir tank via the bypass circuit BPe having the second check valve CV2 provided at the other end of the second hydraulic cylinder 3b. It is discharged to T.

Then, the stroke length of the first piston 4a is automatically corrected. An electric signal which detects that the first piston 4a has reached the position detecting switch S1 is supplied to the solenoid 15 of the pilot pressure switching valve 9 to switch the switching valve 7 as shown in FIG. The SC is actuated as indicated by an arrow to switch the oscillating pipe 31 to a position 31R indicated by a solid line in FIG. 8 (A), and the electric signal detected by the position detection switch 11a is transmitted to the solenoid valve 12 of the pilot pressure switching valve 8. , And is operated as indicated by the arrow in FIG.

Also, as shown in FIG.
When b reaches the stroke end on one end side of the second hydraulic cylinder 3b and the first piston 4a does not reach the position detection switch S2 provided on the other end side of the first hydraulic cylinder 3a, the hydraulic oil amount of the closed circuit M Is too small, and the closed circuit M is provided from the P port of the second hydraulic cylinder 3b via the bypass circuit BP1 having the first check valve CV1.
The hydraulic oil is replenished, and the first piston 4a is caused to reach the stroke end on one end side, so that the stroke length of the first piston 4a is automatically corrected.

[0011]

As described above, for example, in a concrete pump, the stroke length of the first and second pistons 4a and 4b is set so that the amount of hydraulic oil in the closed circuit M is always constant. However, since the volume of the hydraulic oil expands or contracts due to a change in the temperature of the hydraulic oil, the stroke length of movement of the piston fluctuates, and this fluctuation is prevented. Therefore, in the case of the stroke correction as described above and the variable type concrete pump (not shown), the hydraulic oil amount is supplied or discharged manually, but it is necessary to open and close the on-off valve, which is troublesome and troublesome. .

Further, depending on the properties of the ready-mixed concrete (hereinafter simply referred to as ready-mixed concrete), that is, in the case of pumping hard ready-mixed concrete, if the strokes of the first and second pistons 4a and 4b are too long, there will be insufficient force when extruding. Therefore, the stroke must be shortened, that is, the pumping amount must be reduced, so that the operation of the piston can be smoothly performed.

In the conventional variable concrete pump, the stroke length changes due to the amount of hydraulic oil in the closed circuit due to leakage at the packing portion and changes in hydraulic oil. If the amount needs to be readjusted and the grease is automatically supplied at the bottom dead center of the concrete pump piston, the grease will not be supplied properly unless the stroke length is readjusted frequently. And so on.

In addition, the fixed concrete pump has an incompatibility in which the stroke length cannot be optimally adjusted according to the state of pumping. The present invention was devised in view of these problems, and provided a plurality of ports in the middle of a hydraulic cylinder to form a bypass circuit, and further provided a gate valve arbitrarily openable and closable in the bypass circuit. The bypass circuit can be selected, and when the piston of the hydraulic cylinder passes through a port position where one of the gate valves is open, the operating oil pressure flows to the hydraulic cylinder on the opposite side through one of the bypass circuits and the position thereof And a hydraulic pump for the fluid pump, wherein the piston stroke length can be selected according to a set position set according to the design specification of the bypass port. The purpose is to:

[0015]

According to a first aspect of the present invention, there is provided a fluid pump for supplying hydraulic pressure to a pair of hydraulic cylinders respectively connected to a pair of fluid pumping cylinders. And a closed circuit formed by communicating the head side of the paired hydraulic cylinders or a sealed circuit formed by communicating the rod side of the paired hydraulic cylinders, and the hydraulic pressure formed by the pair Position detecting means for detecting the positions of a plurality of stroke ends of the piston of the one hydraulic cylinder, which is disposed on one of the hydraulic cylinders and set according to design specifications, and A plurality of bypass circuits having an openable / closable gate valve for communicating a plurality of ports provided in the other hydraulic cylinder with the closed circuit side; A bypass circuit having a check valve for discharging excess hydraulic oil therein, and switching means for switching the switching valve in accordance with the switching signal detected by the position detecting means and activating the paired hydraulic cylinders. And

According to a second aspect of the present invention, there is provided a fluid pump according to the present invention, comprising: a switching valve for switching a circuit for supplying hydraulic pressure to a pair of hydraulic cylinders respectively connected to a pair of fluid pumping cylinders; A closed circuit formed by connecting the head side of the hydraulic cylinder to be connected or a closed circuit formed by connecting the rod side of the pair of hydraulic cylinders to one of the hydraulic cylinders of the pair. Position detecting means for detecting the positions of a plurality of stroke ends of the piston of the one hydraulic cylinder, which are provided according to a design specification, and a plurality of positions provided on the other hydraulic cylinder of the pair of hydraulic cylinders A plurality of bypass circuits having an openable / closable gate valve for connecting the ports to the closed circuit side, and discharging excess hydraulic oil in the closed circuit. A bypass circuit having a check valve, a switching valve for switching a circuit for supplying hydraulic pressure to a swing switching hydraulic cylinder of a swing pipe selectively connected to one of the pair of hydraulic cylinders, and the one piston Switching means for switching the switching valve of the swing switching hydraulic cylinder by detecting a stroke end signal of the cylinder, and switching for switching the switching valve of the hydraulic cylinder by detecting a stroke end signal of the piston of the swing switching hydraulic cylinder. Means, and switching means for switching the switching valve in response to the switching signal detected by the position detecting means to operate the paired hydraulic cylinders.

The hydraulic cylinder of the fluid pump according to the third aspect of the present invention comprises a pair of fluid pumping reciprocating pistons for alternately sucking and discharging the fluid, and In the hydraulic cylinder of the fluid pressure pump having a pair of hydraulic cylinders connected to each of the fluid pressure cylinders, a closed circuit or the pair is formed by connecting the head side of the pair of hydraulic cylinders to each other. A closed circuit formed by connecting the rod side of a hydraulic cylinder to be formed, and an opening and closing for connecting the closed circuit side to a plurality of ports provided in at least one of the paired hydraulic cylinders and the plurality of ports provided in at least one of the hydraulic cylinders And a plurality of bypass circuits each having a possible gate valve.

According to a fourth aspect of the present invention, the hydraulic cylinder of the fluid pressure pump according to the fourth aspect of the present invention is the hydraulic cylinder of the third aspect, further comprising a bypass circuit having a check valve for discharging excess hydraulic oil in the closed circuit. It is characterized by.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic explanatory view showing a hydraulic circuit when a fluid pump according to the present invention is applied to a hydraulic concrete pump, and FIG. 2 is an enlarged view of a hydraulic cylinder portion of FIG. FIG. 3 is an explanatory diagram showing the correction of the first set stroke length of the piston when it is too long, and FIG. 3 is a diagram showing the correction of the stroke length of the piston when the amount of hydraulic oil in the closed circuit on the head side in FIG. 2 is too small. FIG. 4
FIG. 5 shows the correction of the second set stroke length of the hydraulic cylinder, and is an explanatory view showing the same state as in FIG. 2, and FIG. 5 shows the case where the amount of hydraulic oil in the closed circuit of FIG. 3
FIG. 6 is an explanatory diagram showing a state similar to FIG. 7, and FIG. 6 is an explanatory diagram showing a stroke length correction when the amount of hydraulic oil in a closed circuit on the rod side of a hydraulic cylinder operated in a high-pressure circuit is too small.
FIG. 7 is an explanatory diagram showing the correction of the stroke length when the amount of hydraulic oil in the closed circuit on the rod side in FIG. 6 is too large.

As shown in FIG. 1, there is provided a gate housing GH in which a ready-mixed concrete as a fluid is supplied. The gate housing GH communicates with the inside of the gate housing GH which alternately sucks and discharges the ready-mixed concrete in the gate housing GH. As described above, a pair of the first and the first provided outside the gate housing GH.
The second fluid pumping cylinders CCa and CCb are provided.

The first and second fluid pumping cylinders CCa and CCb are provided so as to be connected to the pair of first and second fluid pumping cylinders CCa and CCb, respectively.
The first and second hydraulic cylinders 3a and 3b are provided as pairs of concrete pumps for operating the first and second reciprocating pistons Pa and Pb. An oscillating pipe 31 having one end positioned at least inside the gate housing GH and supported so as to be rotatable around the axis at the other end is provided. The oscillating pipe 31 is selectively connected to one of the first and second fluid pressure feeding cylinders CCa and CCb.
, A swing switching hydraulic cylinder SC that rotates around the axis on the other end side.

The first hydraulic cylinder 3a and the second hydraulic cylinder 3a of one of the pair of hydraulic cylinders for operating the first and second fluid pressure reciprocating pistons Pa and Pb are operated.
A switching valve 6 for switching a circuit for supplying hydraulic pressure to the hydraulic cylinder 3b, and a piston P of a swing switching hydraulic cylinder SC
It has a switching valve 7 that switches a circuit that supplies hydraulic pressure to a swing switching hydraulic cylinder SC that activates S.

A position detection switch S2 is provided at the other end of the first hydraulic cylinder 3a for detecting the position of the stroke end. An electric signal detected by the position detection switch S2 is transmitted to the pilot pressure switching switching valve 9. A switching means T1 is provided for switching the switching valve 7 of the swing switching hydraulic cylinder SC by energizing. Further, there is provided switching means T2 for switching the switching valve in accordance with the switching signal detected by the position detecting means and operating the paired hydraulic cylinders. Also, position detection switches 11a, 11a for detecting the stroke end position of the swing switching hydraulic cylinder SC.
and a switching means T3 for switching the switching valve 6 of the first and second hydraulic cylinders 3a, 3b by energizing an electric signal detected by the position detection switches 11a, 11b to the switching valve 8 for switching the pilot pressure. ing.

The first and second hydraulic cylinders 3a, 3a,
A closed circuit M formed by connecting the heads 3b through the communication path 30 or a communication path between the rod sides of the first and second hydraulic cylinders 3a and 3b shown in FIGS. It has a closed circuit N that is configured to communicate through 30N. In addition, in the present embodiment, a plurality of first pistons 4 arranged in one of the first and second hydraulic cylinders 3a and 3b and set according to design specifications are provided.
Four position detecting means S1 to S4 provided on the first hydraulic cylinder 3a for detecting the position of the stroke end of a are provided.

As shown in FIG. 2, a plurality of, in this embodiment, three ports P1 to P3 provided in the other second hydraulic cylinder of the pair of hydraulic cylinders and the closed circuit side M are connected to each other. Valves V3, V4 that can be opened and closed and first, third, and fourth check valves CV1, CV3, CV
In this embodiment, a plurality of bypass circuits BP1 to BP3 are provided, and a bypass circuit BPe having a second check valve for discharging excess hydraulic oil in the closed circuit M is provided. .

Next, the operation of the above embodiment will be described. First, when the first set stroke end which is set according to the design specification is selected according to the properties of the fluid, for example, the solid ready-mixed concrete, the gate valve V3 is opened and the gate valve V4 is set to be closed in advance. . As shown in FIG. 1, in the hydraulic concrete pump, the first and second hydraulic cylinders 3 of the hydraulic concrete pump are used.
When the first and second pistons 4a and 4b a and 3b are operating in the directions of the arrows, one solenoid valve 12 of the pilot pressure switching valve 8 is closed and the solenoid valve 15 of the other pilot pressure switching valve 9 is closed. Is closed, the switching valve 7 is in the state shown in FIG.
When the first piston 4a of the first hydraulic cylinder 3a reaches the stroke end on the other end side of the first hydraulic cylinder 3a by the hydraulic oil supplied from the second hydraulic cylinder 3a, the other pilot pressure switching valve 9 is turned on by the electric signal of the position detection switch S2. The solenoid valve 14 is energized, and the switching valve 7 of the swing switching hydraulic cylinder SC is switched from the lower side to the upper side in FIG. 1, and the swing pipe 31 is moved to the position 31 indicated by the two-dot chain line in FIG.
Switch to L.

When the hydraulic cylinder SC for swing switching of the swing pipe 31 operates upward from below in FIG. 1 and reaches the stroke end, the position detecting switch 11b
The detected electric signal is supplied to the solenoid valve 13 of one of the pilot pressure switching valves 8, and the switching valves 6 of the first and second hydraulic cylinders 3a and 3b operate in the opposite manner, that is,
In FIG. 1, the first concrete pumping reciprocating piston Pb, which is switched from below to above and is connected to the second piston 4b of the second hydraulic cylinder 3b via the rod Lb, is sucked into the second concrete pumping cylinder CCb. The ready-mixed concrete is discharged to the swinging pipe 31 at the left position 31L shown by the two-dot chain line in FIG. 1 and further supplied to the discharge pipe 33.

As described above, the first and second pistons 4a and 4b of the first and second hydraulic cylinders 3a and 3b and the reciprocating pistons Pa and Pb for pressing the first and second concrete are provided.
Operates in the direction opposite to the arrow shown in FIG. 1, and as shown in FIG. 2, the second piston 4b of the second hydraulic cylinder 3b reaches the stroke end on the other end side of the second hydraulic cylinder 3b, If the first set stroke end set in accordance with the design specification of the piston 4a has not reached the position detection switch S3 provided in the middle of the first hydraulic cylinder 3a and detecting the first set stroke end, the closed circuit M When the amount of hydraulic oil in the inside is too large, the excess amount of hydraulic oil in the closed circuit M is discharged to the reservoir tank T via the bypass circuit BPe having the second check valve CV2.

When the amount of hydraulic oil in the closed circuit M is discharged to the reservoir tank T as described above and decreases, the first piston 4a detects the position of the first set stroke end as shown in FIG. Reaching the detection switch S3, the electric signal detected by the position detection switch S3 is energized to the solenoid 15 of the pilot pressure switching valve 9, and the switching valve 7 and the swing switching hydraulic cylinder SC operate downward from above,
The swing pipe 31 is switched to the position shown in FIG. 1 and is switched to the right position 31R shown by a solid line in FIG.

The swing switching hydraulic cylinder SC
However, an electric signal detected by the position detection switch 11a when the operation is performed from the upper side to the lower side shown in FIG. 1 is supplied to the solenoid 12 of the pilot pressure switching valve 8 so that the switching valve 6
Is switched from above to below, and the first piston 4a reverses so as to operate in the direction of the arrow in FIG. And FIG.
When the first piston 4a is reversed from the state shown in FIG. 2 to the state shown in FIG. 3, as shown in FIG. 2, the first piston 4a is moved to the position detection switch S2 provided on the other end of the first hydraulic cylinder 3a. Works until it reaches the first hydraulic cylinder 3
It reverses at the stroke end on the other end side of a.

When the amount of operating oil in the closed circuit M decreases in the state shown in FIG. 3, the heads of the first and second hydraulic cylinders 3a and 3b are connected by the communication passage 30 during operation. The circuit M is connected to a port P2 provided in the second hydraulic cylinder 3b, and a third check valve CV3,
Hydraulic oil is supplied to the closed circuit M from the P port of the second hydraulic cylinder 3b via the bypass circuit BP2 having the gate valve V3, so that the stroke length of the first piston 4a is automatically corrected.

Next, when the second set stroke end set according to the design specifications is selected according to the properties of the solid raw concrete as a fluid, the gate valve V4 is opened and the gate valve V3 is closed in advance. set. Then, as shown in FIG. 4, the position detection switch S4 for detecting the position of the stroke length of the other second set stroke end set according to the design specification of the first piston 4a and the above-described arrangement. The operation of the bypass circuit BP3 having the fourth check valve CV4 and the gate valve V4 will be described.

As shown in FIG. 4, the second piston 4
If b reaches the stroke end on the other end side of the second hydraulic cylinder 3b and the first piston 4a has not reached the position detection switch S4 for detecting the second set stroke end, the hydraulic oil amount in the closed circuit M Is excessive, the excess amount of hydraulic oil in the closed circuit M is discharged to the reservoir tank T via the bypass circuit BPe having the second check valve CV2 provided at the other end of the second hydraulic cylinder 3b. I'm sullen.

When the amount of hydraulic oil in the closed circuit M is reduced by being discharged from the bypass circuit BPe, the first piston 4a reaches the position detecting switch S4, and the electric signal detected by the fourth detecting switch S4 is used for pilot pressure. Switching valve 9
When the solenoid 15 is energized, the swing switching hydraulic cylinder SC is switched from the upper side to the lower side in FIG. 1 via the switching valve 7, and the swinging pipe 31 is switched to the right position 31R shown by a solid line in FIG.

The position detecting switch 1 detects that the swing switching hydraulic cylinder SC has been switched downward.
When the solenoid signal of the pilot pressure switching valve 8 is energized by the electric signal detected by the switching valve 1a, the switching valve 6 switches from below to above in the direction of the arrow shown in FIG. The ready-mixed concrete in the cylinder 3a is discharged to the discharge pipe 33 via the oscillating pipe 31.

Then, the first piston 4a is inverted and reaches the position detecting switch S2 provided at the other end of the first piston 4a shown in FIG. 5 for detecting a stroke end from the state shown in FIG. It works until you do. And FIG.
As described above, when the amount of hydraulic oil in the closed circuit M is decreasing, the valve is closed from the P3 port of the second hydraulic cylinder 3b through the fourth check valve CV4 and the gate valve V4 of the bypass circuit BP3 during operation as described above. Since hydraulic oil is replenished into the circuit M, the stroke length of the piston is automatically corrected, and stable raw concrete set according to design specifications can be supplied.

The standard hydraulic circuit of the above-described embodiment shown in FIGS. 1 to 5 is connected to the first and second hydraulic cylinders 3a and 3b via a communication passage 30 and connected to the head side. However, in the case where the hydraulic pressure shown in FIGS. 6 and 7 is a high pressure circuit, the rod sides of the first and second hydraulic cylinders 3a and 3b are connected by a communication passage 30N. To form a closed circuit N.

That is, in the case of the high-pressure circuits shown in FIGS. 6 and 7, the operation of correcting the stroke of the piston in the case of the standard hydraulic circuits shown in FIGS. First, the gate valve V3 is closed and the gate valve V
Set 4 to open. An example of the operation when the first set stroke end set as described above is used will be briefly described with reference to FIGS.

In FIG. 6, the second piston 4b of the second hydraulic cylinder 3b is connected to the second hydraulic cylinder 3b by the port P2.
(A position corresponding to the second set stroke end), and the first piston 4a of the first hydraulic cylinder 3a has not reached the position detection switch S3 for detecting the position of the first set stroke end. This is because the amount of hydraulic oil in the closed circuit N is too small. The port P2 on the head side of the second hydraulic cylinder 3b, the port P2, the third check valve CV3, the port 3, the gate valve V3, and the port P
1. The stroke length of the first piston 3a is automatically corrected by replenishing the working oil into the closed circuit N through the communication passage 30N.

In the case shown in FIG. 7, the second piston 4b reaches the stroke end at one end of the second hydraulic cylinder 3b, and the first piston 3a is provided at the other end of the first hydraulic cylinder 3a. If the position of the first piston 3a has not reached the position detection switch S2, the amount of hydraulic oil in the closed circuit N is too large. The stroke length of the second piston 4a is automatically corrected by discharging to the reservoir tank T from the discharge port on the head side of the second hydraulic cylinder 3b through the bypass circuit BPe having CV1.

The operation other than the above is substantially the same as that of the standard hydraulic circuit shown in FIGS.
Further, in the above-described embodiments shown in FIGS. 1 to 7, the case where the above-described bypass circuits BP1 to BP3 are provided only in the second hydraulic cylinder 3b has been described. The bypass circuits BP1 to BP3 are provided in both the first hydraulic cylinder 3a and the second hydraulic cylinder 3b, and the gate valves V3, V4 according to the set stroke lengths of the first and second pistons 4a, 4b. The stroke end can be adjusted with higher accuracy by appropriately providing and operating a position detection switch and the like.

In the above embodiment, the position detection switch S
1 and S2 detect the stroke ends at one end and the other end of the first hydraulic cylinder 3a, which detect the stroke ends at one end and the other end of the first concrete pressure feeding cylinder CCa. Alternatively, the position detection switches S3 and S4 may be provided not in the middle of the first hydraulic cylinder 3a but in the middle of the concrete pressure feeding cylinder CCa, and substantially the same operation and effect as described above can be obtained.

The opening and closing of the gate valves V3 and V4 provided in the bypass circuits BP1 to BP3 are performed by radio communication so that when one of them is open, the other is closed.
Providing interlocking means such as electrical and mechanical means can improve the working efficiency and reliability. (1). In the above example, the switching valve switches between the two types of hydraulic cylinders. However, the switching valve is not limited to the number and type of actuators, and the switching valve is not limited to the number and type.

(2). The position detection switch is not limited to the above embodiment, but may be any position detection means such as a proximity sensor, a reed switch or the like, which can detect the stroke end position of the cylinder. (3). The location where the above signal is taken out is not limited to the energized location of the solenoid, and the piston position detection signal,
It may be from anywhere between the detection signal and the solenoid.

[0045]

As described in detail above, claim 1 or 2
According to the described fluid pump of the present invention, a switching valve for switching a circuit for supplying hydraulic pressure to a pair of hydraulic cylinders,
A closed circuit formed by connecting the head side of the paired hydraulic cylinders or a closed circuit formed by connecting the rod sides of the paired hydraulic cylinders; and one of the paired hydraulic cylinders Position detecting means for detecting stroke end positions of a plurality of pistons of the one hydraulic cylinder, which is provided in the hydraulic cylinder and set according to design specifications, and provided in the other hydraulic cylinder of the pair of hydraulic cylinders A plurality of bypass circuits having an openable and closable valve for communicating the plurality of ports and the closed circuit side with each other; a bypass circuit having a check valve for discharging excess hydraulic oil in the closed circuit; Switches the circuit that supplies hydraulic pressure to the swing switching hydraulic cylinder of the swinging pipe that is selectively connected to one of the paired hydraulic cylinders A switching valve for detecting the stroke end signal of the piston of the swing switching hydraulic cylinder to switch the switching valve of the hydraulic cylinder for feeding fluid, and the switching by the switching signal detected by the position detecting means. Since switching means for switching valves and operating the paired hydraulic cylinders are provided, a plurality of the bypass ports are provided so as to be selectable, thereby selecting the stroke length of the piston of the fluid pressure pump. This makes it possible to select the optimum stroke length in accordance with the state of the fluid being pumped, thereby expanding the range of the fluid that can be pumped and improving the working efficiency.

The selected stroke length is
Even if the amount of hydraulic oil in the closed circuit of the hydraulic cylinder changes, the piston always operates up to the set stroke length, so there is no need to adjust the amount of hydraulic oil during operation, and the operation is performed with maintenance free. Thus, the burden on the operator can be effectively reduced, and the work efficiency can be improved.

According to a third aspect of the present invention, there is provided a hydraulic cylinder of a fluid pressure pump according to the present invention. Each of the pair of reciprocating fluid pressure pistons sucks and discharges a fluid alternately. Cylinder, and a hydraulic circuit of a fluid pressure pump having a pair of hydraulic cylinders connected to the fluid pressure cylinder, respectively, wherein a closed side circuit is formed by connecting the head side of the pair of hydraulic cylinders to each other. Or a closed circuit formed by connecting the rod sides of the paired hydraulic cylinders to each other, a plurality of ports provided at least in the middle of at least one of the paired hydraulic cylinders, and the closed circuit. And a plurality of bypass circuits having an openable and closable sluice valve that communicates with the side, so that when the sluice valve provided in the bypass circuit is opened, When the hydraulic cylinder piston passes the port position where the gate valve is open, the operating oil pressure flows through the bypass circuit to the opposite hydraulic cylinder, so the hydraulic cylinder piston is stopped at that position and the bypass port is installed. The piston stroke length can be selected according to the position.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view showing a hydraulic circuit when a fluid pressure pump according to the present invention is applied to a hydraulic concrete pump.

FIG. 2 is an explanatory diagram showing an enlarged hydraulic cylinder portion in FIG. 1 and showing a correction of a first set stroke length of a piston when the amount of oil in a closed circuit is too large.

FIG. 3 is an explanatory diagram showing correction of a stroke length of a piston when the amount of hydraulic oil in a closed circuit on the head side in FIG. 2 is too small.

FIG. 4 is an explanatory diagram showing correction of a second set stroke length of the hydraulic cylinder, showing a state similar to FIG. 2;

FIG. 5 is an explanatory diagram showing a case where the amount of hydraulic oil in the closed circuit of FIG. 4 is reduced, and showing a state similar to FIG. 3;

FIG. 6 is an explanatory diagram showing stroke length correction when the amount of hydraulic oil in a closed circuit on the rod side of a hydraulic cylinder that operates in the high-pressure circuit of the embodiment is too small.

FIG. 7 is an explanatory diagram showing correction of a stroke length when the amount of hydraulic oil in a closed circuit on the rod side in FIG. 6 is too large.

8 (A) is a schematic explanatory view showing a hydraulic circuit of a conventional hydraulic concrete pump, and FIG. 8 (B) is a schematic explanatory view showing a hydraulic circuit of the conventional hydraulic concrete pump. It is a schematic electric circuit diagram which shows only a main part.

FIG. 9 is an enlarged view of the hydraulic cylinder portion of FIG. 8A and is an explanatory diagram showing correction of a stroke length when the amount of oil in the closed circuit is too large.

FIG. 10 is an explanatory diagram showing correction of a stroke length when the amount of hydraulic oil in a closed circuit on the head side in FIG. 9 is too small.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Oil pump 2 Hydraulic switching valve block 3 Hydraulic cylinder 3a, 3b 1st, 2nd hydraulic cylinder 4a, 4b 1st, 2nd piston 5 Main relief valve 6,7 Switching valve 8,9 Pilot pressure switching valve 11a, 11b Position Detection switch 12 to 15 Solenoid valve 31 Swing pipe CV1 to CV4 Check valve CCa, CCb Concrete pump cylinder P1 to P3 Port Pa, Pb Reciprocating piston for concrete pump PS Piston of hydraulic cylinder for swing change SC Hydraulic cylinder for swing change S1 to S4 Position detection switch (position detection means) M, N Closed circuit V3, V4 Gate valve

Claims (4)

[Claims] 1. A switching valve for switching a circuit for supplying hydraulic pressure to a pair of hydraulic cylinders connected to a pair of fluid pressure feeding cylinders, and a head side of the pair of hydraulic cylinders communicating with each other. A closed circuit formed by connecting the rod side of the pair of hydraulic cylinders or a closed circuit formed by connecting the rod sides of the pair of hydraulic cylinders, and the closed circuit provided in one of the paired hydraulic cylinders and set according to design specifications. A position detecting means for detecting a plurality of stroke end positions of a piston of one hydraulic cylinder, and a plurality of ports provided on the other hydraulic cylinder of the pair of hydraulic cylinders communicate with the closed circuit side. A plurality of bypass circuits having a gate valve that can be opened and closed, a bypass circuit having a check valve for discharging excess hydraulic oil in the closed circuit, A switching means for switching the switching valve in accordance with the switching signal detected by the position detecting means to activate the pair of hydraulic cylinders. 2. A switching valve for switching a circuit for supplying hydraulic pressure to a pair of hydraulic cylinders connected to a pair of fluid-pressure-feeding cylinders, and a head side of the pair of hydraulic cylinders. A closed circuit formed by connecting the rod side of the pair of hydraulic cylinders or a closed circuit formed by connecting the rod sides of the pair of hydraulic cylinders, and the closed circuit provided in one of the paired hydraulic cylinders and set according to design specifications. A position detecting means for detecting a plurality of stroke end positions of a piston of one hydraulic cylinder, and a plurality of ports provided on the other hydraulic cylinder of the pair of hydraulic cylinders communicate with the closed circuit side. A plurality of bypass circuits having a gate valve that can be opened and closed, a bypass circuit having a check valve for discharging excess hydraulic oil in the closed circuit, A switching valve for switching a circuit for supplying a hydraulic pressure to a swing switching hydraulic cylinder of a swing pipe selectively connected to one of the pair of hydraulic cylinders, and a signal of a stroke end of the one piston is detected. Switching means for switching the switching valve of the swing switching hydraulic cylinder, switching means for switching the switching valve of the hydraulic cylinder by detecting a stroke end signal of a piston of the swing switching hydraulic cylinder, and the position detecting means. Switching means for switching the switching valve in response to the detected switching signal to operate the paired hydraulic cylinders. 3. A pair of fluid pumping reciprocating pistons for alternately sucking and discharging a fluid, and a pair of fluid pumping cylinders and a pair of hydraulic pressures connected to the respective fluid pumping cylinders. A closed circuit formed by connecting the head side of the pair of hydraulic cylinders or a closed circuit formed by connecting the rod side of the pair of hydraulic cylinders in a hydraulic cylinder of a fluid pressure pump having a cylinder. And a plurality of bypass circuits having an openable / closable sluice valve for communicating a plurality of ports provided in at least one of the pair of hydraulic cylinders with the closed circuit side. A hydraulic cylinder of a fluid pressure pump. 4. The hydraulic cylinder for a fluid pump according to claim 3, further comprising a bypass circuit having a check valve for discharging excess hydraulic oil in the closed circuit.